CALIFORNIA ACADEMY OF SCIENCES. 39 



One gram of the finely powered mineral was treated with 5 c. 

 c. pure hydrofluoric acid and 5 c. c. pure strong sulphuric acid 

 in a large platinum capsule, evaporated cautiously to dryness 

 and ignited at a dull red heat — the residue boiled with distilled 

 water repeatedly and the lixivium decanted upon a filter — the 

 filtrate made slightly ammoniacal and the lime precipitated 

 therefrom by oxalate of ammonia in slight excess. After standing 

 for 12 hours, the liquid was decanted upon a Swedish filter and 

 passed iuto a platinum capsule of known weight — the residue 

 upon the filter thoroughly washed with boiling distilled water — 

 the filtrate evaporated to dryness on a water bath — the residue 

 ignited at a dull red to eliminate the ammoniacal salts and the 

 capsule weighed. It showed no appreciable increase in weight 

 and therefore soda is present in mere traces only. This result 

 was confirmed by a check experiment. 



Thus far I have proved the mineral to contain water, lime and 

 boracic acid. That none of the boracic acid is present in the 

 free or uncombined state I took the precaution to prove by the 

 spectroscope. 



It now remained to make a careful quantitative estimation of 

 these three essential constituents. 



One gram of the finely powdered mineral weighed in a dry 

 platinum crucible and heated in a hot- water oven at 100° C. for 

 one hour suffers no loss. The hygroscopic water is therefore nil. 



Estimation of the combined water. One gram of the finely 

 powdered mineral was heated cautiously over a Bunsen burner 

 in a tube of hard Bohemian glass about 150 mm. long and 19 

 mm. dia. Through the tube a current of air dried by passing 

 through concentrated sulphuric acid, and then through a chloride 

 of calcium bulb tube, was aspirated. The vaporized water was 

 collected in a system of previously weighed chloride of calcium 

 tubes, and their increase of weight noted on a second weighing. 



During this process a very characteristic phenomenon takes 

 place. At a heat below dull red, decrepitation sets in and the 

 particles of the mineral, however finely pulverized, break up 

 into a still finer dust, whose particles are so minute as to be 

 suspended in the air of the tube for some time, and with the 



